How do politicians manage to believe such things?

Tim Farron, South Lakes MP and chair of the all-party parliamentary hill farming group, said: "We need to do all we can to support our farming industry, particularly in the uplands where life can be a real struggle. This support and funding could make a massive difference to upland farmers throughout Cumbria and help show the next generation that there is a real future in a career in farming."

It appears to me to be an example of cognitive dissonance. For we're also being told this about that same occupation:

An upland farmer earns, on average, only £6,000 a year, which has led to a number of people leaving the industry.

That you can only earn £6,000 a year as an upland farmer is proof perfect that there is not a real future in a career in this type of farming. It is true that not everyone is paid their marginal product but for self-employed people like these hill farmers it is indeed so. Their earnings are exactly the measure of the value that their labours are adding. And given that we're in a country where the GDP per capita is some £25,000 (recall, this includes all of those who do not contribute to the money economy at all) they are producing remarkably little value as compared to the rest of us.

This is telling us that hill farming is something we should stop doing therefore, not something we should be devising ways to prop up. We would all be richer if these farmers simply stopped and went off to do something else.